Hot water boiler



Nov. 29, 1960 H. VORKAUF 2,962,004

HOT WATER BOILER Filed July 8. 1953 I 2 Sheets-Sheet 1 Inventor:

A'r'roRMEY Nov. 29, 1960 H. VORKAUF 2,962,004

HOT WATER BOILER Filed July 8. 1953 2 Sheets-Sheet 2 Inventor 471 0 IYNEY HOT WATER BOILER Heinrich Vorkauf, Davoser Strasse 2b, Berlin-Schmargen-dorf, Germany Filed Juiy 8, 1953, Ser. No. 366,761

Claims priority, application Germany July 15, 1952 1 Claim. (Cl. 122-406) The invention relates to hot water boilers formed only by tubes. Such hot water boiler is frequently employed as a part of the circulation of a conventional heating system. The expansion vessel, which is necessary on account of the expansion of the water in the whole heating system, is generally installed in another place independent of the boiler.

atentC n is an object of the invention that the boiler shall be 7 provided with unheated short circuit or recirculation tubes between the distributors and collectors of the radiantly heated tubes. These short circuit tubes shall be arranged in the corners of the boiler and the headers of the tubes on the front, side and backwall shall be connected to the mentioned short circuit or corner tubes. The described arrangement has the advantage of equalizing the distribution of the water in the tube systems of the boiler.

It is advantageous, to arrange corner tubes in all four corners and to form with the headers and connection tubes a tube cage, which is the frame-work for the heating surface and the casing. It can happen, that in such a tube cage material stresses may arise on account of the temperature differences betwen the return water and the heated water. To prevent those stresses, according to the invention, the heating surfaces connected to the tubes forming the mentioned framework comprise a heated surface with forced circulation and a heated surface with natural circulation, the corner tubes being the short circuit tubes of the heating surface with natural circulation. With this arrangement it is possible to heat up first the return water in the surface with forced circulation and after that let it flow into the tubes of the tube cage. In this manner the temperature-difference between the water entering and leaving the tube cage is small, so that the stresses in the material of the tubes is diminished. The arrangement of heating surfaces with forced and natural circulation has the advantage that the circulation through the heating surface with natural circulation continues even if the circulating pump of the heating system pump ing the water through the forced circulation surface should fail. Therefore the surface with natural circulation is arranged in the hottest part of the boiler especially in the radiant part. In consequence, the flue gases will be cooled down so far before they contact the surface with forced circulation that this surface will not be materially damaged should the pump fail.

The water circulation in the forced circulation tubes can be efficient in either direction from the lower level to the upper or vice versa. The upward flow usually has the advantage of providing a positive distribution of the water but occasions may arise when a downward flow may be necessary for good distribution.

The invention is described hereinafter and illustrated in the drawing by way of example. Fig. l to 3 are diagrammatic illustrations of different embodiments respectively.

Further objects and details of the invention will be apparent from the description given hereinafter and the ice accompanying drawing showing two embodiments thereof by way of example. In the drawing:

, Fig. 1 is a longitudinal cross-section of a boiler according to the invention;

Fig. 2 is a horizontal cross-sectionof the boiler along lines 2-2 of Fig. 1, and

Fig. 3 is a longitudinal cross-section similar to Fig. 1 of a second embodiment.

Referring now to the drawings, in Figs. 1 and 2 the tube cage with the heating surfaces connected to this cage are shown to make the idea of the invention clear. The conventional firing equipment, brickwork and insulation are also indicated. The tube cage consists of the vertical tubes 1, the upper and the lower longitudinal tubes 2 and 2 and the transverse tubes 3, 4 and 5. The heating surfaces are connected to the tube cage. The surface with natural circulation consists of the front wall tubes 6, the back wall tubes 7 and the side Wall tubes 8. The front and back wall tubes are connected to the distributors 4 and 5 and the common collector 3. The side wall tubes extend from the distributors 2' and open into the upper longitudinal tubes 2 which are connected to the collectors 3, The heating surface with forced circulation is formed by several parallel tube coils with their distributor 10 and collector 11. The collector 11 is connected by the tubes 12 with the lower longitudinal tube 2 of the tube cage. The return water enters the distributor 10, flows through the forced circulating heating surface 9 in an upward direction, and is led through tube 12'to the lower longitudinal and transverse tubes of the tube cage from where it flows to the groups 6, 7 and 8 of the heating surface. The hot water is collected in the collector 3 and by tube 13 it flows back to the intake of the heating system (not shown).

By the preheating of the return water in the forced circulation surface 9 the difference of the temperature between inlet and outlet is diminished so that the possibility of stresses in the material is decreased.

The water circulating in the boiler tubes which are functioning under natural circulation is independent of the water circulating in the main heating system under pumped circulation. If the rate of circulation in the latter is increased there will be a partial recirculation in tube 1. The convection tubes which function under forced circulation are free to expand and contract and being made in sections are individually inexpensive and can be easily replaced. The tubes heated by radiation functioning under natural circulation being independent of the circulating pump of the heating system are not affected if that pump fails.

As water in the tube surface 9 flows upward and in the tube surface 12 downward steam or air will collect at the highest point and it is a part of this invention that a deaerating tube 14 connects that point with one of the longitudinal or transverse tubes 1, 2, and 3 of the tube cage. The tube 14 will be looped because the expansion of the tube 12 may not be the same as the expansion of the tube 1.

In the hot water boiler according to Fig. 3 the water is pumped into the boiler by a circulating pump which is part of the heating system. This boiler has two groups of heating surfaces, the water flowing through the first of these groups due to the effect of the circulating pump in the heating system and through the second surface by natural circulation, recirculating tubes being provided for this purpose. These tubes are arranged in the corners and form a boiler tube framework. It is part of the present invention that the collector of the first surface shall be connected to corner tubes leading the water to the lower distributors of the second heating surface group. The other corner tubes are the recirculation tubes of the second heating surface groups.

In Fig. 3 the return water coming from the heating system enters the distributor 21 of the heating surface 22 and is collected in the collector 23. The tube '35 is for the deaerating of collector 23 because the water is led down by the front corner tubes 24 to the transverse distributor 25, both the side wall distributors 26 and the rear transverse distributor 27. The water flowing upward in the surfaces 28, 29 and 30 is collected in the collectors 31, 32 and'flows through the pipe 33 back to the heating system. In the corners of the back wall the recirculation tubes 34 are located, making a circulation in the surfaces 28, 29, 30 possible. This is important in the case the circulating pump of the heating system should fail or the water quantity pumped into the boiler should not correspond to the heat absorption of the boiler. If this water quantity is too small, steam in the hot water boiler would be generated and it is advantageous to have a recirculation for this purpose.

The water flow in the surface 22 may be downwards in counter fiow to the gases. In this case the lower header of surface 22 is connected to the corner tubes. A connection of these corner tubes with the top collectors on the water side may also be provided.

I claim:

In aheating system of the forced circulation type ineluding a circulating pump and a hot water boiler, said boiler comprising a plurality of serpentine tubes forming at least a major portion of a convection heating surface, a second heating surface including a plurality of upwardly directed tubes heated predominantly by radiation, a first distributor connected between said pump and said convection heating surface, at least one first collector connected to said convection heating surface, at least one lower second distributor connected to said second heating surface, a pipe connecting said first collector with said second distributor, a second collector including upper longitudinal tubes connected to the outlet ends of at least some of the tubes of said second heating surface, a hot water outlet connected to said second collector, at least one return pipe connected between said second collector and said second distributor, and an elastic deaerating tube of convoluted shape connected between said first and said second collectors.

References Cited in the file of this patent UNITED STATES PATENTS 1,823,050 Kerr Sept. 15, 1931 1,992,955 Kerr Mar. 5, 1935 FOREIGN PATENTS 494,237 Belgium Mar. 31, 1950 834,454 France Aug. 16, 1938 

